Various polymer concrete compositions are known in the art. As used herein, the phrase “polymer concrete” generally refers to composite materials that contain a polymer matrix impregnated or co-mingled with inorganic particulates. Alternatively, an inorganic material, such as portland cement (hardened or fresh), can be co-mingled with a liquid monomeric compound, which is then polymerized in place to yield the final composition. If the cement portion of the composite is fresh, then the polymerization reaction and the concrete hardening reaction are usually performed simultaneously. Other composite materials referred to herein as a “polymer concrete” do not contain a cement component per se. Rather these types of materials are composites that include a polymer matrix and an inorganic filler that itself is not a “cement,” but an aggregate (e.g., gravel, sand, and the like) or a fine inorganic powder (e.g., silica, talc, and the like). Both types of composite materials fall within the term “polymer cement” as used herein. Polymer cements also generally include some type of catalyst to speed the polymerization reaction that binds the inorganic materials and the polymeric materials into a cohesive whole.
See, for example, U.S. Pat. No. 6,048,593, issued Apr. 11, 2000, to Espeland et al. The Espeland et al. patent describes a castable polymer concrete composition that includes an unsaturated vinyl ester resin and an unsaturated polyester resin as the polymeric portion of the composite. Added to this polymer mix is about 10 to 40 wt % of a filler material having an average particle size of less than about 500 μm, and about 20 to 60 wt % of a filler material having an average particle size of from about 500 to 1,000 μm (the wt % being based on the total weight of the composition). The filler material is noted as including crystalline silica, amorphous silica, barium sulfate (baryte), mica, and glass or ceramic microspheres. See also U.S. Pat. No. 6,034,155, issued Mar. 7, 2000, to Espeland et al.
Polymer concrete compositions can be used in assorted fields, including in the fabrication of leak-proof storage containers. See, for example, U.S. Pat. No. 4,911,326, issued Mar. 27, 1990, to McGouran, Jr. In the McGouran patent, an underground storage tank includes an inner storage tank, that is surrounded by an outer containment shell fabricated from a polymer concrete. The primary purpose of the McGouran device is as an underground storage tank for gasoline. In the McGouran patent, the polymer concrete generally includes a polymer resin such as unsaturated polyester, epoxy, polystyrene, polymethyl methacrylate, and polyfuran resins. The inorganic filler used by McGouran is granite
Polymer concrete composites can be remarkably durable. They can also have very desirable qualities, such as resistance to salts, acids, bases, and other corrosive materials. Thus, in additional to containment structures, polymer concrete materials are also used for fabricating pipes, tunnel support linings, bridge decks, counter-tops and sinks, corrosion-resistant electrolytic containers, and the like. See, for example, U.S. Pat. Nos. 4,545,886; 5,075,065; 5,118,540; and 5,441,772.
A more complex type of composite material is described in U.S. Pat. No. 5,866,273, issued Feb. 2, 1999, to Wiggins et al. Here, the composite is formed of iron-silica complexes which have been processed to yield particulate material having a protective shell. These particles are then bound together with a polymeric matrix to yield a radar-absorbing composite material.